The present invention relates to an improvement of the coal mining method at the long wall face of coal mine and an improvement in a coal mining machine employed to attain this improved coal mining method.
As shown in FIG. 1, the conventional coal mining methods, particularly, of moving-back type employed at the long wall face of coal mine comprise previously providing an intake tunnel (A) and an exhaust tunnel (B) at the both sides of coal bed, arranging the coal mining machine such as a ranging drum shearer and the groups of self-advancing supports in front of the long wall face, and operating the combination of shearer (D) and supports (E) to shear the long wall face in the direction shown by an arrow. When the operational condition is bad, for example, the roof of mine is likely to fall, both sides of long wall face which abut the intake and exhaust tunnels, respectively, are likely to partially break down during the coal mining operation, hindering the intake and exhaust of air to and from the long wall face, so that the coal mining operation must be stopped, thereby lowering the coal mining efficiency. This difficulty has previously been avoided by shearing the long wall face to leave safety walls, which are one to three meters wide, at both sides of the long wall face, or by arranging props by manual labor at both sides of the long wall face. However, in the former case, the operation site is closed by the safety walls from the intake and exhaust tunnels and, therefore, the safety walls must be partially broken by manual labor using the drill and dynamite to form openings communicating the operation site with the intake and exhaust tunnels. In the latter case, too, the props must be shifted by manual labor. Since the inhaling of floating dusty materials by the laborers must be avoided for sanitary reasons, these operations of partially breaking the safety walls, particularly, the one left at the exhaust side of long wall face and of shifting the props in both cases make it necessary to temporarily stop the coal mining operation, thus substantially lowering the coal mining efficiency.